[pbs-devel] [PATCH v2 proxmox-backup] fix: avoid loss of concurrent config changes during datastore deletion

[Robert Obkircher]

Fix a race between the initial reading of the datastore config before
destroying the datastore and concurrent config changes, by re-reading
the config in a locked context before removing the just destroyed
datastore from it.

Previously, the following steps created files in /srv/test2 but
removed test2 from the configuration:

  proxmox-backup-manager datastore create test1 /srv/test1
  proxmox-backup-manager datastore remove test1 --destroy-data &
  sleep 0.1
  proxmox-backup-manager datastore create test2 /srv/test2

Reported-by: https://forum.proxmox.com/threads/174715/
Signed-off-by: Robert Obkircher <r.obkircher at proxmox.com>
Reviewed-by: Christian Ebner <c.ebner at proxmox.com>
Tested-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-datastore/src/datastore.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index 03830616..14dad93a 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -2154,6 +2154,8 @@ impl DataStore {
         if ok {
             info!("Removing datastore from config...");
             let _lock = pbs_config::datastore::lock_config()?;
+            // read again to avoid loosing concurrent modifications
+            let (mut config, _digest) = pbs_config::datastore::config()?;
             let _ = config.sections.remove(name);
             pbs_config::datastore::save_config(&config)?;
         }
-- 
2.47.3